The present invention relates to a canister type filter mounting and more particularly to such a filter when used in combination with a fluid reservoir.
Hydraulic equipment is driven with hydraulic fluid under pressure supplied by a hydraulic power unit. These hydraulic power units primarily consist of a reservoir for the hydraulic oil or fluid and a pump to pump the hydraulic fluid out from the reservoir under pressure. The oil has to be continuously filtered to remove unwanted residue and impurities. A spin-off canister type replaceable filter is generally employed in direct conjunction with the oil reservoir for periodic changing of the filter.
Typically, these hydraulic power units have inlet and outlet piping for the canister filters which is mounted above the top closure of the hydraulic fluid reservoir. The filter is mounted in an inverted position to a filter mount that is supported from these fluid inlet and outlet pipes which extend vertically from and through the top closure of the hydraulic fluid reservoir.
The problem with this type of prior art structure is that the inlet and outlet hydraulic fluid pipes and the mount and the filter canister itself are awkwardly exposed above the reservoir whereby they are exposed and subject to damage. In addition, the appearance of this type of prior art filter assembly tends to be unsightly and when changing filter canisters, invariably messy oil spills or hydraulic fluid spills will occur spilling oil over the top of the hydraulic fluid reservoir and other equipment on the hydraulic power unit. This is so even though the filter canister mount is positioned such that the canister is mounted in an inverted or upsidedown position, as small amounts of oil remain in the feed lines of the filter mounting which is positioned above the inverted filter canister.
In an attempt to avoid these problems, one additional prior art filter canister mounting arrangement provides a filter mounting housing on top of the hydraulic fluid reservoir cover and the filter canister is secured downwardly on this filter mount such that the canister is held in an upright position. In order to assist in preventing leakage of oil from the filter canister when removing it, a check valve is provided in the canister to retain the oil in the canister in order to inhibit the spillage of oil over the top of the reservoir tank.
However, this latter mentioned prior art system is also not completely effective as residue oil will coat interior parts of the canister which bypass the check valve. Accordingly, oil spillage will still occur on the upper surface of the reservoir tank and also the filter canister mounting is exposed on top of the reservoir tank which further tends to make the overall appearance of the hydraulic power units less aesthetically appealing.